JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
September 2018
D-P02

Signalment (JPC#3104060/WSC 08-09 4/3):  A male New Zealand white rabbit.

HISTORY:  Clinically normal animal, incidental finding at necropsy.

HISTOPATHOLOGIC DESCRIPTION:  Liver:  Multifocally bile ducts are tortuous and markedly ectatic (up to 4 mm), and often compress surrounding hepatic parenchyma.  Ectatic ducts are expanded by hyperplastic biliary epithelium which forms branching papillary projections consisting of a single layer of columnar to cuboidal epithelial cells supported on a moderate fibrovascular stroma.  Epithelial cells frequently have karyorrhectic, karyolytic, or pyknotic nuclei (necrosis).  The hyperplasic biliary epithelium contains myriad developing coccidial life stages including many protozoal macrogametes and microgametes in various stages of gametogony.  The macrogametes are round, 20-50 um in diameter, with a central nucleus, prominent nucleolus, and brightly eosinophilic 3-4 um diameter peripheral granules.  The microgametes are round, 15-25 um in diameter, with peripheral lightly basophilic granules.  Within the lumen and within epithelial cells there are moderate numbers of thin walled oocysts, gametocytes and cellular debris.  The unsporulated oocysts are oval, 20-40 um in diameter with thick refractile walls that are often collapsed and contain lightly basophilic and eosinophilic, granular cytoplasm with a central eosinophilic nucleus. There are few intra or extracellular 10-30um meronts which contain numerous 1X4um crescent shaped merozoites.  Ectatic bile ducts are surrounded by a narrow rim of fibrous connective tissue, moderate numbers of lymphocytes, fewer macrophages and plasma cells, and low numbers of degenerate neutrophils, along with increased clear space and ectatic lymphatics (edema).  Diffusely, there is mild chronic portal and periportal lymphoplasmacytic inflammation.

MORPHOLOGIC DIAGNOSIS:  Liver:  Cholangitis, proliferative and lymphoplasmacytic, chronic, multifocal, severe, with ductular ectasia, fibrosis, and numerous intraepithelial macrogamonts, microgamonts and intraluminal oocysts, etiology consistent with Eimeria stiedae, New Zealand white rabbit (Oryctolagus cuniculus), lagomorph.

ETIOLOGY:  Eimeria stiedae

ETIOLOGIC DIAGNOSIS:  Hepatic eimeriosis

GENERAL DISCUSSION:

LIFE CYCLE:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Baker, DG. Natural pathogens of laboratory mice, rats, and rabbits and their effects on research. Clin Microbiol Rev. 1998;11(2):231-266.
  2. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Blackwell Publishing; 2016:297-300.
  3. Uzal FA, Platter BL, Hostetter JM. Alimentary System. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St Louis, MO: Elsevier; 2016: 227-239.
  4. Gardiner CH, Fayer R, Dubey JP. An Atlas of Protozoan Parasites in Animal Tissues. 2nd ed., Washington, DC: Armed Forces Institute of Pathology;1998:20-30.
  5. MacDonald AM, Jardine CM, Reiman E, et al. High Prevalence of Mycoplasma and Eimeria Species in Free-Ranging Eastern Wild Turkeys (Meleagris gallopavo silvestris) in Ontario, Canada. J Wildl Dis. 2018; June 27: doi: 10.7589/2017-11-273. [Epub ahead of print].


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